Underreamer.



F. F-iTCHETT.

UNDERREAMEIL( APPLICATION FILED Amm, |916.

l l 97,47 1 Patented Sept. 5, 1916.

i ik 5w z f t immessi.. l 12 l 'Indem fmeia www ir uur ad iliilimfr U NERREAM EE.

To all whom t 'may omwm'n f Be it known ther L FRANK FrTCHE'm; a citizen o1" he Unto States of America, and; resident of` the' city of Calgary, in the Provinoe of Alberto., oniirlion of Camelia, have inventori certain new and useful nrprove- .merits in Uiirierremners, of which 'the foi- 'owingg ie the speoioation.

This invention rebates to improi/emeirts in under remmers and. the objects of the invention are to so oon-eroi the bits of rire refimer that they are rmtexxmizieaii-y ezipaiifed imo the opereve posraiom to facilitate in re moving the bits in @me of repair or renewa, if.: simiiiy the oonszruoion and overcome the deieee generaljy iounc in @he sei/ferai rares oi the remmers at presern in use whereby strength and 'durability are prf vided anni the iiabilitv 'of breakage is greatly Ciecreased or almost entirely obvia'ed. y

-'Wiloh the above objects in 'View he im'ei tion consists esseotinliy of the ,improved construction pmisioulariy described mi Sei; forth iii the following epecioaon and aoeompanjving drawings; forming mrt of the same. I

En the drawings, Figure is a iongiudr nai section of' die improved under reamer showing zhe bits expanded in :i Working position. fr. 2. is a iongitmiinal section of the improved und J reame? showing; the same being extracted fir-031:1 e bore with the bits in @dosed or inoperniive 'ioeitiorr Fig; 3 is a transverse sto-ation aioiig hedine 3-3 of Fig., l

Like characters of reference refer to iire parte in tne Seremi figures,

Referring; to the drawings, represente the improved under remmer comprising; the n'mridrel t? making ihre ded erggzigijeriient ai; the opper emi with the :sha k Lo which roem-jy merio-n may be applied in any cori-` venien; and suitable nimmer. The manre 2 is provi wiili on enim'ged central bore is inceseci at. the upper end by eubsorr- 'emily conical Wai! connected by arte'pered or commi Wai with o substantmily cylin- Serial No. $5,640.

rieai W211i Ga, the lower end of which i@ beveled Shown at if', wiie rie lor/'er erm. of the mandre termiufmezg in a eheuier che object of' which wii 53 nit/:de elem' here after. lt will. be dearly geen ber, he senr oai wail 5 and the tapered. end 3' of the chamber fc are disposed et Sunstentieii the same angie so that Lhejv are in. eiizoemeni;` This chamber is provided with a. irene verseiy exendirig recess 18 oiosed at one emi the W211i 18', the other end beine" per 'ialiy closed toward the 'top by the We i lib5 both of which weils are 'provided with. iet conduite 205 while the lower end @if the 'Well 13b is provided 'wi mi or" i9 through which. a., key l5 may be irisergei into rire said reoese.

A plunger 'rod 3.1 siidrbigv opere'es i enlarged and reduced bores and z v iis upper emi threafled and provided X a mit l?? engaging with a waeher which concis with the lippe emi oil a spiral spring; "i2 surrouriding the upper poriozu ou? the 'piunfger :mii having; 'lower eind engaging' with he Siwuider Tri miie the lower emi of 5@ the plunger is mode substantially emi. provided with :i slot errgagirigr the key 15. rhe key' 'i5 ie to oporatireify secure the bits l in position and o hie end the upper end of the hits are provide with oriiiees if? it'iierezhrougii miente@ to eine; the key, 'Lfiie bits being; adapted ro noarch :ifa their cerii'er point 16 @fomit which they are Capable of 'being rnziged.

The upper ends of? die nits are tapered and formed wi'flii reoessec portions in adapted to embrace the lower squared emi othe plunger rod 1l and when the bits iii e non-operative posiaion the oi feces of he smid zepered ends are'idepted to ii@ @5 parallel with each other and errug@ ergfege the parallel Weils 6a of 'the chamber fi., lie bits being provicie ioermefiiae of `.wei ends with shouders d "to abiti; with the lower end Q3 rhenandrei end be ing further provide wir@ shouders adapted io ooaeo wi'di Jj-le iorver be? e of the shoe Si of the oz I C.

The assemb'y of rire reamer i f understood from *die {ereg/auw ri now inserted .in the casing C and it will be seen that in iis'position the plunger 11 is displaced downwardly compressing the sprin 12, and when the mandrel has been 4passe through the casing C so that the bits 1l project heyond the shoe 21 of the said casing the spring 12 exerting a pull on the' plunger 11 forces the same upwardly and pulls the upper tapered ends of the bits 1 into .engagement with the conical wall 5 and vtapered .edge 7 of the chamber et forcing the bits llateinldy outiif'ardly at their lower ends to engage the periphery of the hole which is being under reamed.

I It will be noticed that when the bits 1 are expanded the ley 15 is drawn toward the upper end of the recess 18 and the said key cannot in. any way become displaced since its longitudinal motion is limited by the end walls 18 and 18 of the said recess. ln withdrawing the reamer from a hole when the operation of' under reaming has been completed the beveled end of the shoe 21 engages with the shoulders 24 closing the bits toward each other and displacing the plunger l1 downwardly so that the bits assume a position shown in Fig. 2, and 1t will be again noticed that the key cannot become displaced while passing through the casing C since if there were any tendency of its working through the orifices 19 it would be prevented from so doing by the walls of the casing.

As many changes could bev made in the above construction and many apparently widely different embodiments of my invention, within the scope of the claim, constructed without departing from the spirit or scope thereof, it is intended that all matter contained in the accompanying specification and drawings shall be interpreted as illustrative and not in a limiting sense.

llVhat ll claim as my invention is:

. An under reamer comprising a mandrel having a. central bore and provided at the lower end with a chamber inclosed atthc .upper end by conical walls and at the lower end by a cylindrical wall having a beveled lower edge formed in alinement with the upper conical wall and having a transversely extending recess therein closed at one end and partly open at the other end, a plunger slidably operated in the bore having a square lower end and an orifice there- 

